Manufacture of ceramic objects and the like



Dec. 6, 1966 E. D. MILLER, JR

MANUFACTURE OF CERAMIC OBJECTS AND THE LIKE Filed April 13, 1964 5Sheets-Sheet 1 MWE/VTO/P ELDON D. MILLER, JR. Q/hawk AT QRWEY Dec. 6,1966 0. MILLER, JR 3,290,421

MANUFACTURE OF CERAMIC OBJECTS AND THE LIKE Filed April 13, 1964 5Sheets-Sheet 2 llVVE/VTOA? ELDON D.MILLER,JR.

Dec. 6, 1966 E. D. MILLER, JR

' MANUFACTURE OF CERAMIC OBJECTS AND THE LIKE Filed April 13, 1964 5Sheets-Sheet 5 M l EWTOR.

ELDON D. MILLER, JR. BY I f M ffl fl aa ATTORNEY United States Patent3,290,421 MANUFACTURE OF CERAMIC OBJECTS AND THE LIKE Eldon D. Miller,.Ir., Bridgeville, Pa, assignor to Harbison- Walker RefractoriesCompany, Pittsburgh, Pa., a corporation of Pennsylvania Filed Apr. 13,1964, Ser. No. 359,145 6 Claims. (Cl. 2642l9) sequently, can bedisassembled easily.

There are several known processes for the formingof ceramic andrefractory shapes or objects, and they probably oan be classified mosteasily according to the nature or state of the ceramic or refractorymaterial which is used. The three classes which I would suggest are:

(I) slip processes,

(H) plastic processes, and

(III) dry press methods such as, for example, forming on a mechanicalbrick press, a runner brick press, an impact press, etc.

The present invention is applicable only to groups I and II, and has norelation to group III.

The so-called slip processes use relatively finely divided argillaceousmaterials and the like in an aqueous suspension or emulsion, with orwithout the addition of powdered frits, fluxing ingredients such asfeldspar, and the like. The suspension is quite fluid. I know of the useof organic fluids such as alcohols, esters and ketones, in place of thewater, as the carrier medium for the finely divided materials which areused in slip processes. The slip is poured into a porous mold, usuallyof gypsum plaster or a similar moisture-absorbent substance, which moldtakes up the water or fluid from the slip to produce a self-sustaininggreen object of the desired shape.

The so-called plastic processes are really quite similar to the slipprocesses, the primary differences residing in sizing of the ingredientsand the quantity of tempering agent or carrier liquid which is mixedwith the solids. For example, the materials used in the slip processesare probably all -325 mesh; and certainly no particles are larger than100 mesh.' The solids-liquid weight ratio is probably on the order ofabout 1 to 1. In contrast the so-called plastic processes can use verycoarse material. For example, 4-0 or 50% of the solids can be 3+2:8mesh. I have successifullly used even coarser particles; for example, onthe order of A, as about 5 or of the total solids. The tempering fluidor carrier agent is usually water mixed with a dispersing agent; forexample, sodium pyrophosphate. The tempering fluid is present in anamount in the range 5 to 10%, based on the weight of the solids. Whenthis solids-liquid mixture is cast into moisture-absorbent molds, thereis usually jiggering and tampering or vibration to consolidate the castmaterial and remove entrapped air. 'Ihese plastic mixes, while I am notsure they can be correctly termed thixotropic, do exhibit manyproperties one would expect to be associated with such a material.

Molds, which are used in both the slip and plastic processes, can be anyof a wide variety of shapes, sizes, configurations, and also can becomposed of varying numbers of components. My invention has particularapplicability to the so-called plastic processes and molds of themulticomponent type. As will be developed hereafter, its many anchorthese elements in place.

benefits can also be enjoyed in the so-called slip processes.

When the object to be cast by the slip or plastic process is ofrelatively simple shape, such as, generally cubic, ovoid, hemispherical,etc., the molds are quite simple. When these simple shapes are toinclude a single internal aperture or cavity, mold preparation is stilleasy. I am here referring to such cavities as one might expect in a cupor vase, refractory nozzle, etc. More serious problems arise, however,when one wishes to fabricate a ceramic or refractory piece which is tohave a plurality of internal passages or cavities, etc., which areseparated from each other by relatively thin walls. It is even morediflicult when these internal cavities or passages are required to havea precise, accurate relation to each other. For example, assume onewishes to cast a honeycomb-like structure having a plurality ofuniformly dimensioned passages therethrough, which passages are ofregular, but noncircular, cross section; for example, triangular,square, hexagonal, etc., and in which certain surfaces or walls ofrespective pass-ages must be accurately positioned relative to eachother. For example, consider a group of passages each of which forms ahexagon, and that eachhexagonal passage is required to have its flatwalls almost perfectly parallel with the wall surfaces of all adjacentpassages. When such specifications are to be met in the casting of arefractory or ceramic shape, mold manufacture is replete with problems.The mold has a plurality of mold components, which have to be accuratelypositioned relative to each other before casting can take place. Theseplural components must be substantially immovable during the castingoperation to obtain the required alignment of adjacent walls in aresulting cast shape. Using prior techniques of mold construction, onewould make a series of hexagon-shaped moisture-absorbent mold piece,each one having a metal rod extending from the bottom probablyexteriorly threaded, which threaded end would be fastened in acomplementarily threaded aperture in another mold piece to align it andhold it in place. Sometime the threaded rod passes completely throughanother one of the components to be fastened in place by a wing nut orthe like. However, these methods of threading and, otherwise,mechanically fastening the pieces are extremely burdensome and timeconsuming; since, as each one is put in place, one must be careful notto disturb it or cause it to rotate slightly, as each one subsequentlyplaced of the components is hand aligned with previously positionedones. This system of assembly requires use of measuring tools ordevices, such as, calipers, rulers and the like. Still further, sincevibration is usually necessary when casting plastic mixes, themechanical fasteners loosen and allow mold parts to wobble out of place.

Accordingly, it is a primary object of this invention to provide amethod of manufacture of moisture-absorbent multi-component molds of thetype used to cast ceramic and refractory materials, which methodprovides for the rapid and accurate assembly of the components, withoutthe use of external measuring devices, and which are easily disassembledand removed from a cast piece.

Briefly, according to one aspect of the invention, my method for themanufacture of multi-components molds comprises the steps of:

Preparing a group of master patterns for the moistureabsorbent moldcomponents. Of course, the master patterns cooperate to provide apositive image of a unit to be cast in an assembled, completed,moisture-absorbent mold. A plurality of flexible anchor elements aremade of a rubber or rubber-like material. These anchor elements includea polarized aperture or passage. They further include an externalsurface configuration arranged to cooperate with the material from whichthe moistureabsorbent mold components are themselves made to A pluralityof these flexible anchor elements are attached in an accurate pattern toone or more of the master patterns in predetermined positions. Thesepositions determine the later assembly of at least some other of themoisture-absorbent mold components. The material of which the moldcomponents are to be made is cast over the master pattern in the usualmanner, and in such a way as to firmly anchor the flexible anchorelements within the bodies of at least some of the moistureabsorbentmold components. However, they are so incorporate-d in respectivemoisture-absorbent mold components as to expose and allow easy access tothe polarizing apertures, above noted. In my preferred embodiment, thispolarizing aperture is a hexagonal passage. The hexagonal passagesthrough the plurality of anchor elements are, of course, related to eachother in a predetermined manner; since it is these passages which, inlarge part, later firmly fix and hold some of the moisture-absorbentmold components in desired position and relationship to each other.Those moistureabsorbent mold components, which must be accuratelypositioned, include a pin of hexagonal shape arranged to be inserted inselected ones of the flexible anchor elements. I suggest brass pins.These pins are of slightly larger cross section than the polarizingapertures in which they are to be inserted. Since the anchor elementsare flexible, they give somewhat when the pins are inserted to frictionally hold them, and the mold components of which the pins are apart, in place. Still further, because of the flexible character of theanchor elements, the pins are removed easily after a ceramic orrefractory shape has been cast. Even more useful is that vibration of anassembled mold does not loosen or move the mandrels.

Other objects and further features and advantages of mold construction,and resulting molds, according to the teachings of this invention, willbecome readily apparent to those skilled in the refractory and ceramicarts from a study of the following detailed description, together withreference to the appended exemplary drawings. In order to facilitateexplanation, I have selected an exemplary complicated shape which can becast in a mold constructed according to the invention. Other shapes andarrangements, of course, lend themselves to manufacture according to theconcepts set forth herein. Therefore:

In FIG. 1 there is shown a perspective view of a complicated ceramicpiece having a plurality of accurately aligned passages formedtherethrough, which passages are of hexagonal, cross-sectionalconfiguration, and which piece is made in molds fabricated according tothis invention;

In FIG. 2 there is shown a perspective view of a mold fabricatedaccording to the concepts of this invention, which can be used to castthe piece of FIG. 1;

FIG. 3 is a perspective view of some of the components used to assemblethe mold of FIG. 2;

FIG. 4 is a perspective view of the mold elements of FIG. 3 as they areassembled, and indicating placement of internal mandrels to form thepassages in the cast shape of FIG. 1;

FIG. 5 is a perspective view of a master pattern, usable to make anelement of FIGS. 2 through 4, in an initial stage of assembly;

FIG. 6 is a perspective view of one of the moistureabsorbent mandrelsshown in FIG. 4; and

FIG. 7 is a perspective view of one of the pins upon which the mandrelsof FIG. 6 are mounted.

I show, in FIG. 1, a shape or plate which is usable, for example, as afluid bed support. It is designed to allow maximum fluid flow. Toproperly control fluid flow, it is required that the apertures orpassages, which are formed by the honeycomb network of refractory orceramic which constitutes the shapes, be accurately aligned in apredetermined pattern. It should be understood this environment of useand the shape, itself, are strictly for the purposes of explanation inthis case; and are indicative only of the type of casting problem whichcan be solved by the invention. The shape 10 is generally rectangular inhorizontal cross section, is relatively thin as compared to width, andhas a plurality of regular hexagonal passages 11 formed through it.These passages are defined by the interconnected honeycomb network ofrefractory webs 12. The webs 12 are quite thin, at least as compared tothe thickness of the shape. The hexagonal passages are so arranged as toprovide maximum open space through the plate 10, commensurate withstructural integrity and strength for subsequent use. All adjacent facesor walls which form adjacent passages are parallel. Consider, forexample, the passages 11A and 11B. Faces 12A and 12B are substantiallyparallel, as are respective immediately opposed faces in a commonpassage.

The shape of FIG. 1 is made in the mold assembly of FIG. 2. The moldassembly is comprised of a plurality of moisture-absorbent moldcomponents, including the base plate 15, the back plate 16 and the twomirror-image side forms 17 and 18. A plurality of moisture-absorbentmandrels 19 (these mandrels are, themselves, mold components) areaccurately positioned within the upwardly opening void formed by theassembled base plate, back plate and side forms.

Each of the mandrels 19 includes a pin or stem 20. Referring for themoment to FIGS. 6 and 7, the mandrels 19 are hexagonal in shape, and areof such dimensions as to form the passages 11 of the shape of FIG. 1.They have a slight downward taper from one end to the other; forexample, from the top of FIG. 6 to the bottom thereof, to facilitateremoval from a cast shape. By slight taper, I mean, for example,considering a mandrel about 2 in vertical extent, the downward taper isabout per foot. However, as one can see, opposed walls or faces in anaperture or passage made by the mandrel 19 are substantially parallel.The cross section of pins 20 is hexagonal or noncircular. This is topolarize them to hold the mandrels in place. The pin cross sectionalconfiguration, of course, could be square, triangular, oval, etc. At aposition intermediate its longitudinal extent, each pin 20 has a fewgrooves or notches 21 formed. Only sufiicient notches 21 are formed, ascan be encompassed within the body of the mandrel 19; and their onlypurpose is to firmly anchor a pin 20 within the body of mandrel 19. Theycould be glued or one could depend on frictional engagement to hold thepin and mandrel together, but I prefer to notch the pins. Still further,the pin and mandrel could be cast as one piece when the mold material isof sufficient strength. In any event, the pin or equivalent must extendoutwardly from the top and the bottom faces of the mandrel. Oneextending end mates with a polarizing anchor element, such as the oneshown in FIG. 5, which will be discussed later, and the other end is toallow manual removal and insertion of the mandrel pin assembly asrequired.

In FIG. 4, I have shown the mold of FIG. 2 at an intermediate stage ofits assembly. A group of mandrels and pins have been assembled, and aworker is shown inserting an additional one 20X in one of the resilientanchor-,

ing devices 30. The anchoring device 30, as perhaps shown more clearlyin FIG. 5-which shows a master pattern used to manufacture the baseplate 15, has an irregular external surface configuration, to assurefirm and immovable anchoring in the body of the base plate 15. I haveshown an anchor element which is hexagonal in cross section and having acircumferential depression 31 formed intermediate its ends. Theanchoring element, further, has an internal polarizing aperture orpassage 32, which is arranged to receive, align and releasably, grip anextending end of one of the pins 20.

The cross section of a passage 32 is, preferably, smaller than the crosssection of the extending end of a pin 20. For example, a diametermandrel pin 20 is inserted in a passage or aperture 32 on the order of Ain diameter.

slightly Anchor elements 30 are fiexible. They are cast or fabricated ofa flexible rubber or rubber-like material of sufficient elasticity togive slightly when a pin 20 is inserted in a passage 32. Still further,when a pin 20 is inserted, some of the anchor element substance isdisplaced upwardly a slight distance above the flat upper surface of thebase plate. The bottom of mandrel 19 is thus supported slightly out ofcontact with the base plate and overcomes the possibility of chippingedges thereof as might occur if placed directly against the base plate.Its rubber-like character also serves to frictionally engage a pin 20,which frictional engagement is easily overcome when one Wishes to liftthe mandrel upwardly from a cast shape.

The bottom plate master pattern 40 of FIG. 5 conventionally isfabricated of wood. A plurality of apertures has been formed through itsupper surface to receive the plurality of pins 41. The pins 41 are ofsubstantialy the same cross sectional configuration as the pins 20. Thepins 41 are placed in holes or apertures which are carefully machined inan accurately determined spatial arrangement. Their respective verticalcenter lines will correspond to center lines of the passages 11 in thefinal shape 16 of FIG. 1. In practice, the apertures in pattern 40, intowhich the pins 41 are inserted, are slightly smaller in cross section toallow a firm, drive fit. Thus, in making the pattern of FIG. 5, the pins41 are driven into the accurately aligned holes or apertures formed forthat purpose, and the plurality of the anchoring elements 30 are slippedinto position over these pins 41. They are pressed down firmly so theirlower surfaces are contiguous to and, preferably, in contact with, theupper face or surface of the pattern 40. Wooden side patterns (notshown) are releasably afiixed about the edges or sides of the pattern40, to provide a cavity capable of retaining the material from which themoisture-absorbent base plate is to be made. I have not shown the sideforms in the drawings, since they are merely fiat boards so one can makean open-topped box-like affair, which will hold the cast mold material(for example, gypsum plaster), to a depth equal to the vertical extentof the anchor elements 30, until that material sets. The next step is topour prepared plaster slurry or the like over the anchor elements 30.When a good firm set is obtained in the mold material (this is, ofcourse, variable, but we suggest waiting about an hour when one usesconventional gypsum plaster), the set, moisture-absorbent base plate isremoved from the master pattern. This is easily done by taking off theside forms, gripping the solid plaster piece, and lifting. The anchorelements are permanently positioned Within the body of the resultingbase plate 15, with their upper surfaces exposed substantially as shownin FIG. 3. The side forms 17 and 1S and the back plate 16 are made in asimilar manner, i.e. plaster slurry is poured into a prepared masterpattern, the slurry is allowed to set, and the finished shapes 16, 17and 18 are recovered. As is also conventional, suitable keying structureis formed in the plates. For example, protuberances 50 and 51 are formedin opposed ends of the plate 16, in such a position as to mate with thecomplementary depressions 52 and 53 of the side forms 17 and 18.Respective opposite end surfaces of these side forms have a depression54 and protuberance 55 to mate those respective surfaces. The ridge 56on the upper surface of base plate 15 was formed by the wood strip 40Aon the master pattern of FIG. 5. Complementary grooves 56 and 57 areformed in the side pieces 17 and 18.

After assembly of the mold parts 15, 16, 1'7 and 18, they are heldtogether in a conventional manner, as by rubber bands 60 and 61.

While I have shown protuberances or extending pieces for the mandrelassemblies, such as extending ends of i the pins 20, and complementaryapertures in the anchorthe elements 30, there could be pins or integralprotuberances arranged to seat in complementary keying structure on oneend of the mandrel body 19. In any event, however, the protrudingportion of the keying system for the mandrels and anchoring elements isof hard and hot flexible material such as metal or ceramic; and thecomplementary aperture is of a flexible material.

The novel arrangement of keying elements, in a multicomponent mold madeaccording to the concepts of this invention, allows rapid but veryaccurate assembly of the plural mold parts. An even more beneficialaspect of the arrangement, however, is the speed with which the elementsmay be disassembled; in particular, the speed with which thepassage-forming mandrels can be removed. Well known to those in the art,in casting ceramic and refractory ware of such complex shapes as shownin FIG. 1, a very limited time period exists between initial .set of thecast body and the time at which the cast body shrinks onto internalmolds or mold parts. With prior arrangements where wing nuts, threadedapertures and bolts, etc., were used to lock mandrels in position, oneexperienced considerable difficulty in disconnecting and removing all ofthe internal parts before ware shrinkage fixed the cast part to theinternal parts and caused Ware cracking and breakage. When thisoccurred, the cast piece was a loss. Even more distressing, was the lossof labor required in laboriously assembling the mold components,preparation and casting of the slip or plastic mass, set time, etc.

In the interest of a complete disclosure, Table I sets forth a gypsumplaster chemical analysis (by weight, and on an oxide basis) whichplaster is satisfactory for making mold components.

Table I Silica (SiO 0.3

The gypsum solids are mixed with water in such a ratio as to provideparts of plaster for each 60 parts of water, by weight.

I have mentioned brass for the pins 20 and 41. Other materials, ofcourse, can be used; for example, aluminum, steel, etc. A suitablerefractory mixture, which I have successfully cast in molds madeaccording to the method above, is that described and claimed in myrecent United States Patent No. 3,121,640, issued February 18, 1964, andentitled Alumina Refractories.

In the discussion, above, I have stressed the importance of accuratealignment of anchor elements, mandrels, and pins. To obtain the requireddegree of accuracy, I align corresponding hexagon fiat surfaces. Forexample, when I have positioned a series or line of the mandrelassemblies, pins 41, or the anchor elements, I use a steel straight edgeto be sure all corresponding hexagon flats are straight.

Disassembly of the base plate 16 from the master pat tern 411 isfacilitated if one uses a lubricant for the pins 41 on which the anchorelements 30 are placed; for example, a silicone stop-cock grease. Aparticularly satisfactory material for the manufacture of the elements30 is a commercially available rubber molding compound sold under thetradename Gra-Tufy.

Having thus described the invention in detail and with sufficientparticularity as to enable those skilled in the art to practice it, whatis desired to have protected by Letters Patent is set forth in thefollowing claims.

I claim:

1. Method of manufacturing multi-component moisture-absorbent molds ofthe type used for casting refractory and ceramic ware from slips andslurries, comprising the steps of:

(A) preparing master pattterns for the mold components, which patternscooperate to provide a positive image of a unit to be cast in anassembled completed moisture-absorbent mold;

(B) preparing at least one flexible anchor element arranged to cooperatewith at least a first of the mold components when they are assembled toreleasably hold said first component in place;

(C) temporarily associating the flexible anchor element with a masterpattern in a predetermined position, which position determines the laterassembly of said first mold component relative to a second moldcomponent;

(D) forming moisture-absorbent mold components from the master patternsand anchoring the flexible anchor element in place within the body ofsaid second mold component during the forming of said component;

(E) associating rigid means with said first mold component which meansis arranged to be releasably engaged by said anchor element;

(F) terminating association between the mold components and the masterpatterns to which they are attached and recovering the mold componentsfrom the master patterns, said second mold component having an anchorelement fixed in position therein.

2. Method of manufacturing multi-component mois- "Lure-absorbent moldsof the type used for casting refractory and ceramic ware from slips andslurries, comprising the steps of:

(A) preparing master patterns for mold components, which patternscooperate to provide a positive image of a unit to be cast in anassembled completed moisture-absorbent mold;

(B) preparing flexible anchor elements arranged to cooperate with atleast some of the mold components when they are assembled to releasablyhold these components in place relative to at least one of saidcomponents;

(C) temporarily attaching the flexible anchor elements to at least oneof the master patterns in predetermined positions, which positionsdetermine the later assembly of said at least some of said moldcomponents;

(D) forming moisture-absorbent mold components from the master patternsand anchoring the flexible anchor elements in place within the body ofsaid at least one of the mold components during the forming thereof;

(E) associating rigid means with said at least some of the moldcomponents during fabrication thereof which means are arranged to bereleasably engaged by said anchor elements;

(F) terminating association between the mold components and the masterpatterns to which they are attached and recovering the mold componentsfrom the master patterns.

3. In the method of claim 2, forming externally accessible internalpolarizing means in said anchor elements arranged to mate with saidrigid means to prevent relative rotation of the rigid means to saidanchor elements, when they are engaged by said anchor elements.

4. Method of manufacturing multi-component moisture-absorbent molds ofthe type used for casting refractory and ceramic ware from slips andslurries, comprising the steps of:

(A) preparing master patterns for the mold components, which patternscooperate to provide a positive image of a unit to be cast in anassembled completed moisture-absorbent mold;

(B) preparing a group of flexible anchor elements arranged to cooperatewith a first group of mold components when they are assembled toreleasably hold those components in place relative to a second group ofmold components;

(C) temporarily attaching the flexible anchor elements to masterpatterns in predetermined positions, which positions determine thelatter assembly of the first group of mold components relative to thesecond group} (D) forming said second group of moisture-absorbent moldcomponents from the master patterns to which the flexible anchorelements are attached and permanently seating said elements in place inthe bodies of said second group of mold components during the forming ofsaid components;

(E) associating rigid elements in the bodies of said first group of moldcomponents in position to mate with the anchor elements when the firstand second groups thereof are assembled;

(F) terminating association between the mold components and the masterpatterns to which they are attached and recovering the mold componentsfrom the master patterns.

5. Method of preparing a moisture-absorbent mold for casting a ceramicobject having a plurality of passages formed therethrough in apredetermined spatial arrangement, comprising the steps of: preparing afirst master pattern, forming a series of apertures through a firstsurface of said first master pattern, center lines of said aperturescorresponding to center lines of the passages to be formed in theceramic object to be cast in the moistureabsorbent mold to be made onthe master pattern, preparing a group of rigid pins arranged to befitted in the series of apertures through the first surface of saidfirst master pattern, fixing said pins in said apertures so the centerline of the pins correspond to the center lines of the passages to beformed in said ceramic object to be cast, preparing a series of flexibleanchor elements, forming polarized passages through said flexible anchorelements, placing an element on each of said pins, one end of each ofsaid anchor elements being contiguous to said first surface of saidfirst master pattern, preparing a pourable slurry of moisture-absorbentmold material, pouring said slurry over said first master pattern andcompletely about all of said flexible anchor elements to a depthsubstantially equal to the vertical extent of said flexible anchorelements, allowing the slurry to set to form a moistureabsorbent moldcomponent, removing the set mold component and included flexible anchorelements from the first master pattern and pins, preparing a group ofadditional master patterns arranged to cooperate with said first masterpattern to form an open-topped cavity, pre-- paring a series ofmoisture-absorbent mandrels the cross sectional dimension and verticalextent of which correspond to the cross sectional dimension and verticalextent of the passages to be formed in the ceramic object to be cast,incorporating a rigid pin through each of said mandrels, said pinextending from each end of said mandrel and being positioned along thecenter line of a passage to be formed in a ceramic object to be cast,the cross sectional dimension of the pins in said mandrels beingslightly larger than but of complementary cross sectional dimension tothe polarized apertures formed through said flexible anchor elements,whereby said series of mandrels can be mounted by their pins in saidanchor elements in a predetermined spatial arrangement identical to thearrangement of the plurality of passages to be formed.

6. Method of preparing a moisture-absorbent mold for casting a ceramicobject having a plurality of noncircular passages formed therethroughwhich must be accurately positioned relative to each other in apredetermined spatial arrangement, comprising the steps of: preparing afirst master pattern, fabricating a series of polarizing means on afirst surface of said first master pattern, said series of polarizingmean corresponding in relative positions to the predetermined spatialarrangement of passages to be formed, preparing a group of polarizingmeans arranged to be mated with the series of polarizing means,preparing a series of flexible anchor elements, forming polarized meansarranged to mate with one of said group of polarizing means in each saidflexible anchor element, and mating the series of flexible anchorelements with separate members of the group of polarizing means,preparing a pourable slurry of moisture-absorbent mold material, pouringsaid slurry over said first master pattern and completely about all ofsaid flexible anchor elements to a depth substantially equal to thevertical extent of said flexible anchor elements but exposing therespective polarized means thereof, allowing the slurry to set to form amoisture-absorbent mold component, removing the set mold component andencompassed flexible anchor elements from the first master pattern andgroup of polarizing means, preparing a group of additional masterpatterns arranged to cooperate with said first master pattern to form anopen-topped cavity, preparing a series of moisture-absorbent mandrelsthe cross sectional dimension and vertical extent of which correspond tothe cross sectional dimension and vertical extent of the passages to beformed in the ceramic object to be cast, including polarized means witheach of said mandrels, arranged to mate with the polarized means of ananchor element to position a said mandrel with its center line along thecenter line of a passage to be formed in a ceramic object to be cast,whereby said series of mandrels can be mated with said anchor elementsin a predetermined spatial arrangement identical to the arrangement ofthe plurality of passages to be formed.

References Cited by the Examiner I UNITED STATES PATENTS 771,566 10/1905Nye 264-86 1,526,118 2/1925 Casey 249151 ALEXANDER H. BRODMERKEL,Primary Examiner.

B. SNYDER, Assistant Examiner.

1. METHOD OF MANUFACTURING MULTI-COMPONENT MOISTURE-ABSORBENT MOLDS OFTHE TYPE USED FOR CASTING REFRACTORY AND CERAMIC WARE FROM SLIPS ANDSLURRIES, COMPRISING THE STEPS OF: (A) PREPARING MASTER PATTERNS FOR THEMOLD COMPONENTS, WHICH PATTERNS COOPERATE TO PROVIDE A POSITIVE IMAGE OFA UNIT TO BE CAST IN AN ASSEMBLED COMPLETED MOISTURE-ABSORBENT MOLD; (B)PREPARING AT LEAST ONE FLEXIBLE ANCHOR ELEMENT ARRANGED TO COOPERATEWITH AT LEAST A FIRST OF THE MOLD COMPONENTS WHEN THEY ARE ASSEMBLED TORELEASABLY HOLD SAID FIRST COMPONENT IN PLACE; (C) TEMPORARILYASSOCIATING THE FLEXIBLE ANCHOR ELEMENT WITH A MASTER PATTERN IN APREDETERMINED POSITION, WHICH POSITION DETERMINES THE LATER ASSEMBLY OFSAID FIRST MOLD COMPONENT RELATIVE TO A SECOND MOLD COMPONENT; (D)FORMING MOISTURE-ABSORBENT MOLD COMPONENTS FROM THE MASTER PATTERNS ANDANCHORING THE FLEXIBLE ANCHOR ELEMENT IN PLACE WITHIN THE BODY OF SAIDSECOND MOLD COMPONENT DURING THE FORMING OF SAID COMPONENT; (E)ASSOCIATING RIGID MEANS WITH SAID FIRST MOLD COMPONENT WHICH MEANS ISARRANGED TO BE RELEASABLY ENGAGED BY SAID ANCHOR ELEMENT; (F)TERMINATING ASSOCIATION BETWEEN THE MOLD COMPONENTS AND THE MASTERPATTERNS TO WHICH THEY ARE ATTACHED AND RECOVERING THE MOLD COMPONENTSFROM THE MASTER PATTERNS, SAID SECON MOLD COMPONENT HAVING AN ANCHORELEMENT FIXED IN POSITION THEREIN.